Why is there an extra http code 308 permanent redirect?

I'm using cloudflare to deploy my LP pages, regardless of whether my LP url is “http://xxx.com/a/index.html?x=y” or “http://xxx.com/a?x=y ”,it will return http code 308 and force me to jump to “http://xxx.com/a/?x=y”, I don't understand the reason for this, doesn't it add one more